Spherical trimanganese tetroxide with low bet specific surface area and the method for preparation thereof

Abstract

The present invention provides a spherical trimanganese tetroxide with low BET specific surface area and preparation method thereof. The preparation method of the present invention comprises: (1) pre-treatment process, adding MnS and peroxide to MnSO 4 solution whose concentration is 130˜200 g/L to remove impurities, and then, neutralizing and separating by solid-liquid separation to obtain manganese sulfate filtrate; (2) oxidation reaction process, putting the filtrate in a reactor, maintaining the temperature of the solution at 25˜30° C., spraying the filtrate through the spray nozzle, mixing the sprayed manganese sulfate filtrate with a mixture gas of oxygen and ammonia gas to carry out reaction on the spraying interface at under a pressure of 500˜1000 mm H 2 O, reacting until [Mn 2+ ]≦1.5 g/L, the gas mol ratio is O 2 /NH 3 =1/12; (3) process for obtaining the final product, separating the solution obtained after reaction by solid-liquid separation to obtain solid and filtrate, washing and drying the solid to obtain Mn 3 O 4 product. The trimanganese tetroxide of the present invention has properties that particle size distribution is narrow, the crystal phase is pure, impurities content is low, Mn % is 71.44˜71.08 wt %, BET specific surface area is less than 1 m 2 /g, D 90 is 7.0˜8.5 μm, D 10 is 2.6˜3.2 μm, D 50 is 4.0˜5.5 μm, and D max is 15.138 μm.

1 . A method for preparing spherical trimanganese tetroxide, comprising:
 (1) a pre-treatment process comprising: adding MnS and a peroxide sequentially to a MnSO 4  solution whose concentration is 130˜200 g/L to remove impurities, neutralizing the resulting mixture to pH value of 5.0˜5.5, and separating the mixture by solid-liquid separation to obtain manganese sulfate filtrate;   (2) an oxidation reaction process comprising: putting the foregoing manganese sulfate filtrate obtained in the pre-treatment process (1) in a reactor, spraying the filtrate through a nozzle of the reactor so that the sprayed manganese sulfate filtrate is mixed with mixture of oxygen and ammonia gas introduced into the reactor to carry out circular reaction on the spraying interface at the pressure range of 500˜1000 mm H 2 O and stopping the reaction when the concentration of Mn 2+  reaches 1.5 g/L or less in the reaction solution, wherein the manganese sulfate filtrate is cooled and maintained at a temperature range of 25˜30° C. to carry out circular reaction on the spray interface and mol ratio of oxygen to ammonia gas is O 2 /NH 3 =1/12; and   (3) a process for obtaining the final product comprising: separating the solution obtained after completing the oxidation reaction process (2) by solid-liquid separation to obtain a solid and a filtrate, recovering NH 3  from the filtrate, washing the solid with deionized water, and then drying the solid to obtain Mn 3 O 4  product.   
     
     
         2 . The method for preparing spherical trimanganese tetroxide according to  claim 1 , wherein, in the pre-treatment process (1), MnS is added to the solution to carry out reaction according to the proportion of 2.5˜3.0 kg of MnS per cubic meter of solution. 
     
     
         3 . The method for preparing spherical trimanganese tetroxide according to  claim 2 , wherein, in the pre-treatment process (1), reaction is carried out under agitation for 3˜4 hours at 90˜95° C. after adding MnS. 
     
     
         4 . The method for preparing spherical trimanganese tetroxide according to  claim 1 , wherein, in the pre-treatment process (1), when said peroxide is barium peroxide, barium peroxide is added to the solution according to the proportion of 1.5˜2.2 kg per cubic meter of solution and impurities are removed with oxidation reaction under boiling. 
     
     
         5 . The method for preparing spherical trimanganese tetroxide according to  claim 1 , wherein, in the process of obtaining the final product (3), CaO is added to the filtrate to recover NH 3 . 
     
     
         6 . The method for preparing spherical trimanganese tetroxide according to  claim 1 , wherein, in the process of obtaining the final product (3), the solid is washed with deionized water at a temperature of 70˜80° C. according to the weight ratio of solid to liquid of 1:5. 
     
     
         7 . The method for preparing spherical trimanganese tetroxide according to  claim 1 , wherein, in the process of obtaining the final product (3), said drying is maintained for 23˜26 hours at a temperature range of 100˜110° C. 
     
     
         8 . The method for preparing spherical trimanganese tetroxide according to  claim 1 , wherein, in the process of obtaining the final product (3), said drying is maintained for 24 hours at 105° C. 
     
     
         9 . A spherical trimanganese tetroxide product that is prepared by the method according to  claim 1 . 
     
     
         10 . The spherical trimanganese tetroxide product according to  claim 9 , whose BET specific surface area is less than 1 m 2 /g, D 90  is 7.0˜8.5 μm, D 10  is 2.6˜3.2 μm, and D 50  is 4.0˜5.5 μm. 
     
     
         11 . The spherical trimanganese tetroxide product according to  claim 9 , whose BET specific surface area is 0.7122˜0.8214 m 2 /g, D 90  is 7.029˜8.456 μm, D 10  is 2.626˜3.139 μm, D 50  is 4.302˜5.185 μm, D max  is 15.138 μm, bulk density is 2.31˜2.64 g/cm 3 , and Mn % is 71.44˜71.08 wt %. 
     
     
         12 . The method for preparing spherical trimanganese tetroxide according to  claim 1 , wherein, in the pre-treatment process (1), when said peroxide is hydrogen peroxide, hydrogen peroxide is added to the solution according to 2.5 L of 27.5 wt % hydrogen peroxide per cubic meter of solution and impurities are removed with oxidation reaction under the condition that the mixture is boiling.